🩹 UVB Phototherapy Mechanism Simulator

Why 311nm Narrowband UVB

Narrowband UVB isolates the most therapeutic wavelength band.

• 311 nm: Peak wavelength (narrowband UVB (TL-01))
• 280–320nm: Broadband range (older UVB devices)
• Lower: Erythema efficiency (vs broadband UVB)
• ~70%: Clearance rate (typical psoriasis response)

Spectral targeting of the therapeutic band

311nm targets pathology while sparing surrounding tissue.

Placeholder: narrowband lamps reduce burn risk versus broadband UVB.

Inducing Apoptosis in Pathogenic T-Cells

UVB photons damage DNA in activated dermal T-lymphocytes.

• Th1/Th17: Target cells (psoriatic T-lymphocytes)
• DNA damage: Mechanism (pyrimidine dimer formation)
• ~2–4 wks: Onset (sessions to clinical effect)
• IL-17, IL-23: Cytokine drop (reduced signaling)

Photoimmunology of T-cell depletion

Repeated exposure depletes pathogenic skin-infiltrating T-cells.

Placeholder: apoptosis reduces local inflammatory cytokine load.

Restoring Normal Epidermal Turnover

Keratinocyte division slows from psoriatic to normal rate.

• ~4 days: Psoriatic turnover (vs 28 days normal skin)
• ~28 days: Target turnover (normalized epidermal cycle)
• ↓ over weeks: Plaque thickness (scale and thickness reduce)
• Cytokine drop: Driven by (from T-cell suppression)

Coupling immune signal to keratinocyte cycle

Reduced cytokines slow keratinocyte hyperproliferation.

Placeholder: normalization lags behind immune suppression by design.

Titrating to the Minimal Erythema Dose

Dose is escalated just below the erythema threshold.

• Pre-treatment: MED test (individualized dose baseline)
• 10–20%: Typical increment (per session escalation)
• Minimal pink: Erythema target (sub-blistering threshold)
• I–VI scale: Skin phototype (adjusts starting dose)

Balancing efficacy against burn risk

Dose titration maximizes benefit while limiting erythema.

Placeholder: overshooting MED risks burns and treatment pauses.

Cumulative Dose and Long-Term Skin Cancer Risk

Lifetime UVB exposure is tracked to manage cancer risk.

• Cumulative J/cm²: Risk factor (lifetime dose tracking)
• 20–30 sessions: Typical course (per treatment cycle)
• Annual skin exam: Monitoring (long-term surveillance)
• Lower: Risk vs PUVA (compared to psoralen UVA)

Managing lifetime phototherapy exposure

Cumulative dose logs inform long-term treatment limits.

Placeholder: narrowband UVB carries lower carcinogenic risk than PUVA.